1. Field of the Invention
The present invention relates, generally, to fluid dispensers, and more particularly, to apparatus for dispensing fluids from a pressurized injector barrel reservoir. A closure cap provided by this invention prevents retrogression of the cap from the barrel reservoir and a subsequent loss of air pressure from within the dispenser. This is highly important to the operator who relies on a predictable measure of air pressure inside the barrel reservoir in order to dispense fluids with the precision required to meet industry standards and specifications.
2. Background Information
In the past, various devices and methods have been used or proposed to create and maintain a sealed environment in injector-type barrel reservoir apparatus. Molded plastic closure caps for pneumatic dispensers of fluids such as pharmaceuticals, nutritional supplements, adhesives, lubricants, chemicals, inks and other fluid compositions are in wide use today. A broken seal between the cap and the reservoir is a problem common to this type of dispenser. The subsequent loss of air pressure inside of the dispenser and, depending on the fluid contents in the dispenser, the very real possibility of contamination to the environment or injury to the operator exist and are a serious problem.
The seal can be breached by various ways and means such as pulsating air pressure inside the reservoir or the harsh conditions typically found in stockyards. An operator administering pharmaceuticals or nutritional supplements to livestock must, at times, physically restrain the animals. This is difficult and fatiguing work thereby making applications using pressurized injectors preferable over injections given via hand syringes that are slow, messy, and fatiguing to use. Pneumatic dispensers are preferred when quality-control and safety are a priority. Controlled air-pressure allows the operator to make faster deposits exactly where they are needed without mess and waste. And air-powered dispensers that incorporate adjustable air output provide exact fluid flow control.
Various devices and methods have been used and proposed to overcome the problem of a broken seal between the reservoir and cap of an injector type syringe. However, these devices have significant limitations and shortcomings. Specifically, one prior art apparatus relies on a cooperating locking mechanism to hold the cap in a sealed relationship with the reservoir. The closure cap of the above mentioned prior art includes an annular sealing rib having a generally arcuate mating surface for engagement with the annular planar mating surface of the plastic container. The cap's internal threads engage the reservoir's external threads. As the closure is tightened into sealing relationship with the reservoir, the arcuate mating surface engages the cap's planar mating surface. While this provides a good seal between the closure cap and the reservoir, this arrangement still does not contribute sufficient tension to prohibit a backward creeping action and a possible broken seal between the component parts.
Despite the need for a device and method in the art which overcomes the disadvantages and limitations of the prior art, none insofar is known or has been developed. Accordingly, it is an object of the present invention to provide an improved pressurized barrel injector apparatus which is specifically directed at overcoming all of the problems previously enumerated regarding the performance of a sealing closure cap. This is accomplished through a series of three nodes that provide static pressure on the reservoir's external threading tabs thereby preventing the cap from creeping backward or loosening.